Carbon capture and storage
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2008-07-16T17:10:33Z
83.244.199.2
Removed unsupported assertion that needs some evidence to back it up.
'''Carbon capture and storage''' ('''CCS''') is an approach to [[Mitigation of global warming|mitigate]] [[global warming]] by capturing [[carbon dioxide]] (CO<sub>2</sub>) from large [[Point source pollution|point sources]] such as [[fossil fuel power plant]]s and storing it instead of releasing it into the atmosphere. Although CO<sub>2</sub> has been injected into geological formations for various purposes, the long term storage of CO<sub>2</sub> is a relatively untried concept and as yet (2007) no large scale power plant operates with a full carbon capture and storage system.
CCS applied to a modern conventional power plant could reduce CO<sub>2</sub> emissions to the atmosphere by approximately 80-90% compared to a plant without CCS<ref name='IPCC_CC'>[IPCC, 2005] ''IPCC special report on Carbon Dioxide Capture and Storage''. Prepared by working group III of the . Metz, B., O.Davidson, H. C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. Available in full at [http://www.ipcc.ch/activity/srccs/index.htm www.ipcc.ch]</ref>. Capturing and compressing CO<sub>2</sub> requires much energy and would increase the fuel needs of a coal-fired plant with CCS by about 25%<ref name='IPCC_CC'/>. These and other system costs are estimated to increase the cost of energy from a new power plant with CCS by 21-91%<ref name='IPCC_CC'/>. These estimates apply to purpose-built plants near a storage location: applying the technology to preexisting plants or plants far from a storage location will be more expensive.
Storage of the CO<sub>2</sub> is envisaged either in deep geological formations, in deep ocean masses, or in the form of [[mineral]] [[carbonate]]s. In the case of deep ocean storage, there is a risk of greatly increasing the problem of [[ocean acidification]], a problem that also stems from the excess of carbon dioxide already in the atmosphere and oceans. Geological formations are currently considered the most promising sequestration sites, and these are estimated to have a storage capacity of at least 2000 [[Gigaton|Gt]] CO<sub>2</sub> (currently, 30 [[Gigaton|Gt]] per year of CO<sub>2</sub> is emitted due to human activities<ref>{{cite web | title = Volcanic Gases and Their Effects | url=http://volcanoes.usgs.gov/Hazards/What/VolGas/volgas.html| accessdate=2007-09-07 }}</ref>). [[IPCC]] estimates that the economic potential of CCS could be between 10% and 55% of the total carbon mitigation effort until year 2100 (Section 8.3.3 of IPCC report<ref name='IPCC_CC'/>).
==Cost of CCS==
Capturing and compressing CO<sub>2</sub> requires much energy, significantly raising the running costs of CCS-equipped power plants. In addition there are added investment or capital costs. The process would increase the fuel requirement of a plant with CCS by about 25% for a coal-fired plant and about 15% for a gas-fired plant<ref name='IPCC_CC'/>. The cost of this extra fuel, as well as storage and other system costs are estimated to increase the costs of energy from a power plant with CCS by 30-60%, depending on the specific circumstances.
''' Costs of energy with and without CCS (2002 US$ per [[kWh]])'''
{| class="wikitable"
|- bgcolor="#ececec"
| || '''Natural gas combined cycle''' || '''Pulverized coal'''|| '''Integrated gasification combined cycle'''
|-
|-
| Without capture (reference plant) || 0.03 - 0.05 || 0.04 - 0.05 || 0.04 - 0.06
|-
| With capture and geological storage || 0.04 - 0.08 || 0.06 - 0.10 || 0.06 - 0.09
|-
| With capture and [[Enhanced oil recovery]] || 0.04 - 0.07 || 0.05 - 0.08 || 0.04 - 0.08
|-
| class="tNote" colspan="7" | All costs refer to costs for energy from newly built, large-scale plants. Natural gas combined cycle costs are based on natural gas prices of US$2.80–4.40 per GJ ([[lower heating value|LHV]] based). Energy costs for PC and IGCC are based on [[bituminous coal]] costs of US$1.00–1.50 per GJ ([[lower heating value|LHV]]. Note that the costs are very dependent on fuel prices (which change continuously), in addition to other factors such as capital costs. Also note that for EOR, the savings are greater for higher oil prices. Current gas and oil prices are substantially higher than the figures used here. All figures in the table are from Table 8.3a in [IPCC, 2005]<ref name='IPCC_CC'/>.
|}
The cost of CCS depends on the cost of capture and storage which vary according to the method used. Geological storage in saline formations or depleted oil or gas fields typically cost US$0.50–8.00 per tonne of CO<sub>2</sub> injected, plus an additional US$0.10–0.30 for monitoring costs. However, when storage is combined with [[enhanced oil recovery]] to extract extra oil from an oil field, the storage could yield net benefits of US$10–16 per tonne of CO<sub>2</sub> injected (based on 2003 oil prices). This would likely negate some of the effect of the carbon capture when the oil was burnt as fuel. However, as the table above shows, the benefits do not outweigh the extra costs of capture.
Comparisons of CCS with other energy sources can be found in [[wind energy]], [[solar energy]], and [[Economics of new nuclear power plants]].
==Environmental effects==
The merit of CCS systems is the reduction of CO<sub>2</sub> emissions by up to 90%, depending on plant type.
Generally, environmental effects from use of CCS arise during power production, CO<sub>2</sub> capture, transport and storage. Issues relating to storage are discussed in those sections.
Additional energy is required for CO<sub>2</sub> capture, and this means that substantially more fuel has to be used, depending on the plant type. For new supercritical pulverized coal (PC) plants using current technology, the extra energy requirements range from 24-40%, while for natural gas combined cycle (NGCC) plants the range is 11-22% and for coal-based gasification combined cycle (IGCC) systems it is 14-25% [IPCC, 2005]. Obviously, fuel use and environmental problems arising from mining and extraction of coal or gas increase accordingly. Plants equipped with [[flue gas desulfurization]] (FGD) systems for [[SO2|SO<sub>2</sub>]] control require proportionally greater amounts of limestone, and systems equipped with [[Selective catalytic reduction|SCR]] systems for [[NOx|NO<sub>X</sub>]] require proportionally greater amounts of [[ammonia]].
IPCC has provided estimates of air emissions from various CCS plant designs (see table below). While CO<sub>2</sub> is drastically reduced (though never completely captured), emissions of air pollutants increase significantly, generally due to the energy penalty of capture. Hence, the use of CCS entails a reduction in air quality.
''' Emissions to air from plants with CCS (kg/(MW·h))'''
{| class="wikitable"
|- bgcolor="#ececec"
| || '''Natural gas combined cycle''' || '''Pulverized coal'''|| '''Integrated gasification combined cycle'''
|-
|-
| CO<sub>2</sub> || 43 (-89%) || 107 (−87%) || 97 (−88%)
|-
| NO<sub>X</sub> || 0.11 (+22%) || 0.77 (+31%) || 0.1 (+11%)
|-
| SO<sub>X</sub> || - || 0.001 (−99.7%)|| 0.33 (+17.9%)
|-
| Ammonia || 0.002 (before: 0) || 0.23 (+2200%) || -
|-
| class="tNote" colspan="7" | Based on Table 3.5 in [IPCC, 2005]. Between brackets the increase or decrease compared to a similar plant without CCS.
|}
==CO<sub>2</sub> capture==
Capturing CO<sub>2</sub> can be applied to large point sources, such as large fossil fuel or biomass energy facilities, industries with major CO<sub>2</sub> emissions, [[natural gas processing]], synthetic fuel plants and fossil fuel-based hydrogen production plants. Broadly, three different types of technologies exist: Post-combustion, pre-combustion, and oxyfuel combustion.
*In '''post-combustion''', the CO<sub>2</sub> is removed after combustion of the fossil fuel - this is the scheme that would be applied to conventional power plants. Here, carbon dioxide is captured from [[flue gas]]es at [[Fossil fuel power plant|power station]]s. The technology is well understood and is currently used in other industrial applications.
*The technology for '''pre-combustion''' is widely applied in fertilizer, chemical, gaseous fuel (H<sub>2</sub>, CH<sub>4</sub>), and power production <ref>[http://www.netl.doe.gov/publications/brochures/pdfs/Gasification_Brochure.pdf Gasification Body<!-- Bot generated title -->]</ref> In these cases, the fossil fuel is partially oxidized, for instance in a [[gasification|gasifier]]. The resulting syngas (CO and H<sub>2</sub>) is [[Water_gas_shift_reaction|shifted]] into CO<sub>2</sub> and more H<sub>2</sub>. The resulting CO<sub>2</sub> can be captured from a relatively pure exhaust stream. The H<sub>2</sub> can now be used as fuel; the carbon is removed before combustion takes place.
*In '''[[Oxy-fuel combustion]]''' <ref>''Winner: Restoring Coal's Sheen'', William Sweet, IEEE Spectrum, January 2008. Available in full at [http://spectrum.ieee.org/jan08/5819]</ref> the fuel is burned in oxygen instead of air. To limit the resulting flame temperatures to levels common during conventional combustion, cooled flue gas is recirculated and injected into the combustion chamber. The flue gas consists of mainly carbon dioxide and water vapour, the latter of which is condensed through cooling. The result is an almost pure carbon dioxide stream that can be transported to the sequestration site and stored. Power plant processes based on oxyfuel combustion are sometimes referred to as "zero emission" cycles, because the CO<sub>2</sub> stored is not a fraction removed from the flue gas stream (as in the cases of pre- and post-combustion capture) but the flue gas stream itself. It should be noted, however, that a certain fraction of the CO<sub>2</sub> generated during combustion will inevitably end up in the condensed water. To warrant the label "zero emission" the water would thus have to be treated or disposed of appropriately. The technique is promising, but the initial air separation step demands a lot of energy.
*Plants that produce [[ethanol]] by [[fermentation]] generate cool, essentially pure CO<sub>2</sub> that can be pumped underground.[http://www.energycurrent.com/index.php?id=2&storyid=7910] Fermentation produces slightly less CO<sub>2</sub> than ethanol by weight. World ethanol production in 2008 is expected to be about 16 billion gallons or 48 million tonnes.[http://www.marketresearchanalyst.com/2008/01/26/world-ethanol-production-forecast-2008-2012/]
An alternate method, which is under development, is [[chemical looping combustion]] (CLC). Chemical looping uses a metal oxide as a solid oxygen carrier. Metal oxide particles react with a solid, liquid or gaseous fuel in a [[fluidization|fluidized bed]] combustor, producing solid metal particles and a mixture of carbon dioxide and water vapor. The water vapor is condensed, leaving pure carbon dioxide which can be sequestered. The solid metal particles are circulated to another fluidized bed where they react with air, producing heat and regenerating metal oxide particles that are recirculated to the fluidized bed combustor.
A few engineering proposals have been made for the much more difficult task of capturing CO<sub>2</sub> directly from the air, but work in this area is still in its infancy. Global Research Technologies demonstrated a pre-prototype in 2007 <ref>[http://www.earth.columbia.edu/news/2007/story04-24-07.php First Successful Demonstration of Carbon Dioxide Air Capture Technology Achieved by Columbia University Scientist and Private Company]</ref>. Capture costs are estimated to be much higher than from point sources, but may be feasible for dealing with emissions from diffuse sources like automobiles and aircraft <ref>http://wpweb2.tepper.cmu.edu/ceic/theses/Joshuah_Stolaroff_PhD_Thesis_2006.pdf</ref>.
==CO<sub>2</sub> transport==
After capture, the CO<sub>2</sub> must be transported to suitable storage sites. This is done by pipeline, which is generally the cheapest form of transport. In 2008, there were approximately 5,800 km of CO<sub>2</sub> pipelines in the United States. These pipelines are currently used to transport CO<sub>2</sub> to oil production fields where the CO<sub>2</sub> is injected in older fields to produce oil. The injection of CO<sub>2</sub> to produce oil is generally called "Enhanced Oil Recovery" or EOR. <ref>http://en.wikipedia.org/wiki/Enhanced_oil_recovery</ref>. In addition, there are several pilot programs in various stages to test the long-term storage of CO<sub>2</sub> in non-oil producing geologic formations. These are discussed below.
COA conveyor belt system or ships can also be used. These methods are currently used for transporting CO<sub>2</sub> for other applications.
According to the Congressional Research Service, "There are important unanswered questions about pipeline network requirements, economic regulation, utility cost recovery, regulatory classification of CO2 itself, and pipeline safety. Furthermore, because CO2 pipelines for [enhanced oil recovery] are already in use today, policy decisions affecting CO2 pipelines take on an urgency that is, perhaps, unrecognized by many. Federal classification of CO2 as both a commodity (by the Bureau of Land Management) and as a pollutant (by the Environmental Protection Agency) could potentially create an immediate conflict which may need to be addressed not only for the sake of future CCS implementation, but also to ensure consistency of future CCS with CO2 pipeline operations today. <ref>Paul W. Parfomak and Peter Folger, “CRS Report for Congress: Carbon Dioxide (CO2) Pipelines for Carbon Sequestration: Emerging Policy Issues,” Updated January 17, 2008 (Order Code RL33971) (http://assets.opencrs.com/rpts/RL33971_20080117.pdf)</ref>. For a review of federal jurisdictional issues related to CO2 pipelines and reviewing agency jurisdictional determinations under the Interstate Commerce Act and the Natural Gas Act, see Adam Vann and Paul W. Parfomak, "Regulation of Carbon Dioxide (CO2) Sequestration Pipelines: Jurisdictional Issues", updated April 15, 2008 (Order Code RL34307)(http://opencrs.cdt.org/getfile.php?rid=63645).
==CO<sub>2</sub> storage (sequestration)==
{{main|CO2 sequestration}}
Various forms have been conceived for permanent storage of CO<sub>2</sub>. These forms include gaseous storage in various deep geological formations (including saline formations and exhausted gas fields), liquid storage in the ocean, and solid storage by reaction of CO<sub>2</sub> with metal [[oxide]]s to produce stable [[carbonate]]s.
===Geological storage===
Also known as ''geo-sequestration'', this method involves injecting carbon dioxide, generally in [[Supercritical fluid|supercritical]] form, directly into underground geological formations. [[Oil field]]s, [[gas field]]s, saline formations, unminable [[coal seam]]s, and saline-filled basalt formations have been suggested as storage sites. Various physical (e.g., highly impermeable caprock) and geochemical trapping mechanisms would prevent the CO<sub>2</sub> from escaping to the surface. CO<sub>2</sub> is sometimes injected into declining oil fields to increase oil recovery ([[enhanced oil recovery]]). This option is attractive because the storage costs may be partly offset by the sale of additional oil that is recovered. Disadvantages of old oil fields are their geographic distribution and their limited capacity, as well as that the subsequent burning of the additional oil so recovered will offset much or all of the reduction in CO<sub>2</sub> emissions.
Unminable coal seams can be used to store CO<sub>2</sub> because CO<sub>2</sub> adsorbs to the surface of coal. However, the technical feasibility depends on the permeability of the coal bed. In the process of absorption the coal releases previously absorbed methane, and the methane can be recovered ([[enhanced coal bed methane recovery]]). The sale of the methane can be used to offset a portion of the cost of the CO<sub>2</sub> storage.
Saline formations contain highly mineralized brines, and have so far been considered of no benefit to humans. Saline aquifers have been used for storage of chemical waste in a few cases. The main advantage of saline aquifers is their large potential storage volume and their common occurrence. This will reduce the distances over which CO<sub>2</sub> has to be transported. The major disadvantage of saline aquifers is that relatively little is known about them, compared to oil fields. To keep the cost of storage acceptable the geophysical exploration may be limited, resulting in larger uncertainty about the aquifer structure. Unlike storage in oil fields or coal beds no side product will offset the storage cost. Leakage of CO<sub>2</sub> back into the atmosphere may be a problem in saline aquifer storage. However, current research shows that several ''trapping mechanisms'' immobilize the CO<sub>2</sub> underground, reducing the risk of leakage.
For well-selected, designed and managed geological storage sites, IPCC estimates that CO<sub>2</sub> could be trapped for millions of years, and the sites are likely to retain over 99% of the injected CO<sub>2</sub> over 1,000 years.
===Ocean storage===
Another proposed form of carbon storage is in the oceans. Several concepts have been proposed:
* 'dissolution' injects CO<sub>2</sub> by ship or pipeline into the water column at depths of 1000 m or more, and the CO<sub>2</sub> subsequently dissolves.
* 'lake' deposits CO<sub>2</sub> directly onto the sea floor at depths greater than 3000 m, where CO<sub>2</sub> is denser than water and is expected to form a 'lake' that would delay dissolution of CO<sub>2</sub> into the environment.
* convert the CO<sub>2</sub> to [[bicarbonate]]s (using [[limestone]])
* Store the CO<sub>2</sub> in solid [[clathrate hydrate]]s already existing on the ocean floor<ref>[http://www.spiegel.de/international/world/0,1518,523178-2,00.html "Warning signs on the ocean floor: China and India Exploit Icy Energy Reserves: Part 2: Can a Potential Curse Be Transformed into a Blessing?"]</ref><ref>[http://www.economist.com/displayStory.cfm?story_id=9708477&fsrc=RSS "The great submarine burp"]</ref>, or growing more solid clathrate<ref>[http://www.sciencedaily.com/releases/1999/05/990507071858.htm "Deep-Sea Disposal Of Fossil-Fuel Co2: First Ocean Observations"]</ref>.
The environmental effects of oceanic storage are generally negative, but poorly understood. Large concentrations of CO<sub>2</sub> kills ocean organisms, but another problem is that dissolved CO<sub>2</sub> would eventually equilibrate with the atmosphere, so the storage would not be permanent. Also, as part of the CO<sub>2</sub> reacts with the water to form [[carbonic acid]], H<sub>2</sub>CO<sub>3</sub>, the acidity of the ocean water increases. The resulting environmental effects on [[benthic]] life forms of the [[bathypelagic]], [[abyssopelagic]] and [[hadopelagic]] zones are poorly understood. Even though life appears to be rather sparse in the deep ocean basins, energy and chemical effects in these deep basins could have far reaching implications. Much more work is needed here to define the extent of the potential problems.
The time it takes water in the deeper oceans to circulate to the surface has been estimated to be in the order of 1600 years, varying upon currents and other changing conditions. Costs for deep ocean disposal of liquid CO<sub>2</sub> are estimated at US$40−80/ton{{vague|which tons?}}. (2002 USD) This figure covers the cost of sequestration at the powerplant and naval transport to the disposal site. [2]
The bicarbonate approach would reduce the pH effects and enhance the retention of CO<sub>2</sub> in the ocean, but this would also increase the costs and other environmental effects.
An additional method of long term ocean based sequestration is to gather crop residue such as corn stalks or excess hay into large weighted bales of biomass and deposit it in the [[alluvial fan]] areas of the deep ocean basin. Dropping these residues in alluvial fans would cause the residues to be quickly buried in silt on the sea floor, sequestering the biomass for very long time spans. Alluvial fans exist in all of the world's oceans and seas where river deltas fall off the edge of the continental shelf such as the Mississippi alluvial fan in the [[gulf of Mexico]] and the Nile alluvial fan in the [[Mediterranean Sea]].
===Mineral storage===
<blockquote>"Carbon sequestration by reacting naturally occurring Mg and Ca containing minerals with CO<sub>2</sub> to form carbonates has many unique advantages. Most notably is the fact that carbonates have a lower energy state than CO<sub>2</sub>, which is why mineral carbonation is thermodynamically favorable and occurs naturally (e.g., the weathering of rock over geologic time periods). Secondly, the raw materials such as magnesium based minerals are abundant. Finally, the produced carbonates are unarguably stable and thus re-release of CO<sub>2</sub> into the atmosphere is not an issue. However, conventional carbonation pathways are slow under ambient temperatures and pressures. The significant challenge being addressed by this effort is to identify an industrially and environmentally viable carbonation route that will allow mineral sequestration to be implemented with acceptable economics."<ref>Goldberg, Chen, O’Connor, Walters, Ziock. (1998). "CO<sub>2</sub> Mineral Sequestration Studies in US", National Energy Technology Laboratory. Retrieved June 7th, 2007 from:
http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/6c1.pdf </ref></blockquote>
In this process, CO<sub>2</sub> is [[exothermic|exothermically]] reacted with abundantly available metal oxides which produces stable carbonates. This process occurs naturally over many years and is responsible for much of the surface [[limestone]]. The reaction rate can be made faster, for example by reacting at higher temperatures and/or pressures, or by pre-treatment of the minerals, although this method can require additional energy. The [[IPCC]] estimates that a power plant equipped with CCS using mineral storage will need 60-180% more energy than a power plant without CCS. <ref>[IPCC, 2005] ''IPCC special report on Carbon Dioxide Capture and Storage''. ch.7, p.321, p.330, Prepared by working group III of the Intergovernmental Panel on Climate Change. Metz, B., O.Davidson, H. C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. Available in full at [http://www.ipcc.ch/activity/srccs/index.htm www.ipcc.ch]</ref>
The following table lists principal metal oxides of [[Crust (geology)|Earth's Crust]]. Theoretically up to 22% of this mineral mass is able to form [[carbonate]]s.
{|class="wikitable"
|-
!Earthen Oxide!!Percent of Crust!!Carbonate!![[Standard enthalpy change of reaction|Enthalpy change]]<br />(kJ/mol)
|-
|SiO<sub>2</sub>
|59.71
|
|
|-
|Al<sub>2</sub>O<sub>3</sub>
|15.41
|
|
|-
|CaO
|4.90
|[[Calcium carbonate|CaCO<sub>3</sub>]]
| -179
|-
|MgO
|4.36
|[[Magnesium carbonate|MgCO<sub>3</sub>]]
| -117
|-
|Na<sub>2</sub>O
|3.55
|[[Sodium carbonate|Na<sub>2</sub>CO<sub>3</sub>]]
|
|-
|FeO
|3.52
|[[Iron carbonate|FeCO<sub>3</sub>]]
|
|-
|K<sub>2</sub>O
|2.80
|[[Potassium carbonate|K<sub>2</sub>CO<sub>3</sub>]]
|
|-
|Fe<sub>2</sub>O<sub>3</sub>
|2.63
|[[Iron carbonate|FeCO<sub>3</sub>]]
|
|-
|
|21.76
|All Carbonates
|}
===Leakage===
A major concern with CCS is whether leakage of stored CO<sub>2</sub> will compromise CCS as a climate change mitigation option. For well-selected, designed and managed geological storage sites, IPCC estimates that risks are comparable to those associated with current hydrocarbon activity. CO<sub>2</sub> could be trapped for millions of years, and well selected stores are likely to retain over 99% of the injected CO<sub>2</sub> over 1000 years. For ocean storage, the retention of CO<sub>2</sub> would depend on the depth; IPCC estimates 30–85% would be retained after 500 years for depths 1000–3000 m. Mineral storage is not regarded as having any risks of leakage. The IPCC recommends that limits be set to the amount of leakage that can take place.
It should also be noted that at the conditions of the deeper oceans, (about 400 bar or 40 MPa, 280 K) water–CO<sub>2</sub>(l) mixing is ''very'' low (where carbonate formation/acidification is the rate limiting step), but the formation of water-CO<sub>2</sub> hydrates is favorable. (a kind of solid water cage that surrounds the CO<sub>2</sub>). [3]
To further investigate the safety of CO<sub>2</sub> sequestration, we can look into Norway's [[Sleipner gas field]], as it is the oldest plant that stores CO<sub>2</sub> on an industrial scale. According to an environmental assessment of the gas field which was conducted after ten years of operation, the author affirmed that geosequestration of CO<sub>2</sub> was the most definite way to store CO<sub>2</sub> permanently. [4]
<blockquote>''"Available geological information shows absence of major tectonic events after the deposition of the Utsira formation [saline reservoir]. This implies that the geological environment is tectonically stable and a site suitable for carbon dioxide storage. The solubility trapping [is] the most permanent and secure form of geological storage."'' [4]</blockquote>
Phase I of the [http://www.ptrc.ca/access/DesktopDefault.aspx?tabindex=8&tabid=81 Weyburn] Project in [[Weyburn, Saskatchewan]], Canada has determined that the likelihood of stored CO<sub>2</sub> release is less than one percent in 5,000 years.<ref>Allan Casey, ''Carbon Cemetery'', Canadian Geographic Magazine, Jan/Feb 2008, p. 61</ref>
==CO<sub>2</sub> Reuse==
A potentially useful way of dealing with industrial sources of CO<sub>2</sub> is to convert it into hydrocarbons where it can be stored or reused as fuel or to make plastics. There are a number of projects investigating this possibility<ref name='newsci2645'>New Scientist No2645, 1st March 2008.</ref>.:
===Single Step methods: CO<sub>2</sub> + H<sub>2</sub> → Methanol===
A proven process to produce a hydrocarbon is to make [[methanol]]. Methanol is rather easily synthesized from CO<sub>2</sub> and H<sub>2</sub>. Based on this fact the idea of a [[methanol economy]] was born.
===Single Step methods: CO<sub>2</sub> → Hydrocarbons===
At the department of Industrial Chemistry and Engineering of Materials at the University of Messina, Italy there is a project to develop a system which works like a fuel-cell in reverse, whereby a catalyst is used that enables sunlight to split water into hydrogen ions and oxygen gas. The ions cross a membrane where they react with the CO<sub>2</sub> to create hydrocarbons.
===2 Step methods: CO<sub>2</sub> → CO → Hydrocarbons===
If CO<sub>2</sub> is heated to 2400[[degree Celsius|°C]] then it splits into carbon monoxide and oxygen. The [[Fischer-Tropsch process]] can then be used to convert the CO into hydrocarbons. The required temperature can be achieved by using a chamber containing a mirror to focus sunlight on the gas. There are a couple of rival teams developing such chambers, at [[Solarec]] and at [[Sandia National Laboratory]], both based in New Mexico. According to Sandia these chambers could provide enough fuel to power 100% of domestic vehicles using 5800 km², but unlike biofuels this would not take fertile land away from crops but would be land that is not being used for anything else.
==Example CCS projects==
As of 2007, four industrial-scale storage projects are in operation. [[Sleipner gas field|Sleipner]] [http://www.iku.sintef.no/projects/IK23430000/] is the oldest project (1996) and is located in the North Sea where Norway's [[StatoilHydro]] strips carbon dioxide from natural gas with amine solvents and disposes of this carbon dioxide in a deep saline [[aquifer]]. The carbon dioxide is a waste product of the field's natural gas production and the gas contains more (9% CO<sub>2</sub>) than is allowed into the natural gas distribution network. Storing it underground avoids this problem and saves Statoil hundreds of millions of euro in avoided [[carbon tax]]es. Since 1996, Sleipner has stored about one million [[tonne]]s CO<sub>2</sub> a year. A second project in the [[Snøhvit]] gas field in the [[Barents Sea]] stores 700,000 tonnes per year. <ref>Allan Casey, ''ibid'', p. 63</ref>
The [http://www.ptrc.ca/access/DesktopDefault.aspx?tabindex=8&tabid=81 Weyburn project] is currently the world's largest carbon capture and storage project.<ref>Allan Casey, ''ibid'', p. 63</ref> Started in 2000, Weyburn is located on an oil reservoir discovered in 1954 in [[Weyburn, Saskatchewan|Weyburn, southeastern Saskatchewan]], Canada. The CO<sub>2</sub> for this project is captured at the [http://www.dakotagas.com/Companyinfo/index.html Great Plains Coal Gasification] plant in [[Beulah, North Dakota]] which has produced methane from coal for more than 30 years. At Weyburn, the CO<sub>2</sub> will also be used for enhanced oil recovery with an injection rate of about 1.5 million tonnes per year. The first phase finished in 2004, and demonstrated that CO<sub>2</sub> can be stored underground at the site safely and indefinitely. The second phase, expected to last until 2009, is investigating how the technology can be expanded on a larger scale.<ref>Allan Casey, ''ibid'', p. 59</ref>
The fourth site is [http://www.co2captureandstorage.info/project_specific.php4?project_id=71 In Salah], which like Sleipner and Snøhvit is a natural gas reservoir located in [[In Salah|In Salah, Algeria]]. The CO<sub>2</sub> will be separated from the natural gas and re-injected into the subsurface at a rate of about 1.2 million tonnes per year.
A major Canadian initiative called the [http://www.ico2n.com Integrated CO<sub>2</sub> Network (ICO2N)] is a proposed system for the capture, transport and storage of carbon dioxide (CO<sub>2</sub>). ICO2N members represent a group of industry participants providing a framework for carbon capture and storage development in Canada.
In October 2007, the Bureau of Economic Geology at The University of Texas at Austin received a 10-year, $38 million subcontract to conduct the first intensively monitored, long-term project in the United States studying the feasibility of injecting a large volume of CO<sub>2</sub> for underground storage<ref>"Bureau of Economic Geology Receives $38 Million for First Large-Scale U.S. Test Storing Carbon Dioxide Underground" [http://www.jsg.utexas.edu/news/rels/102407.html]</ref>. The project is a research program of the Southeast Regional Carbon Sequestration Partnership (SECARB), funded by the National Energy Technology Laboratory of the U.S. Department of Energy (DOE). The SECARB partnership will demonstrate CO<sub>2</sub> injection rate and storage capacity in the Tuscaloosa-Woodbine geologic system that stretches from Texas to Florida. The region has the potential to store more than 200 billion tons{{vague}} of CO<sub>2</sub> from major point sources in the region, equal to about 33 years of U.S. emissions overall at present rates. Beginning in fall 2007, the project will inject CO<sub>2</sub> at the rate of one million tons{{vague}} per year, for up to 1.5 years, into brine up to 10,000 feet (3,000 m) below the land surface near the Cranfield oil field about 15 miles (25 km) east of [[Natchez, Mississippi]]. Experimental equipment will measure the ability of the subsurface to accept and retain CO<sub>2</sub>.
Currently, the United States government has approved the construction of what is touted as the world's first CCS power plant, [[FutureGen]]. On January 29, 2008, however, the Department of Energy announced it was withdrawing funding from FutureGen, as it had originally been proposed, casting considerable doubt on the future of the project and in the view of some effectively terminating the project.
Examples of carbon sequestration at an existing US coal plant can be found at utility company Luminant's pilot version at its Big Brown Steam Electric Station in Fairfield, Texas. This system is converting carbon from smokestacks into baking soda. [http://www.skyonic.com/theCompany.php Skyonic ]plans to circumvent storage problems of liquid CO2 by storing baking soda in mines, landfills, or simply to be sold as industrial or food grade baking soda. [http://www.greenfuelonline.com/index.html GreenFuel Technologies Corp.] is piloting and implementing algae based carbon capture, circumventing storage issues by then converting algae into fuel or feed.
[http://www.carbontrap.net Carbon Trap Technologies, L.P.], (“CTT”) was formed in early 2007 to develop and to market a technology to chemically sequester carbon dioxide emissions from fossil fuel combustion, while producing useful products with significant market value.
In the Netherlands, an 68 MW oxyfuel plant ("Zero Emission Power Plant") is being planned and is expected to be operational in 2009<ref>"Demonstration project The Netherlands: Zero Emission Power Plant" [http://www.createacceptance.net/fileadmin/create-acceptance/user/docs/Demonstration_project_The_Netherlands.pdf]</ref>.
In the United States, four different synthetic fuels projects are moving forward which have publicly announced plans to incorporate carbon capture and storage.
American Clean Coal Fuels, in their [http://www.cleancoalfuels.com/cleancoalfuels_projects.html Illinois Clean Fuels] project, is developing a 30,000 Barrel Per Day Biomass and Coal to Liquids project in Oakland Illinois, which will market the CO2 created at the plant for Enhanced Oil Recovery applications. The project is expected to come online in late 2012.
Baard Energy, in their [http://www.baardenergy.com/orcf.htm Ohio River Clean Fuels] project, are developing a 53,000 BPD Coal and Biomass to Liquids project, which has announced plans to market the plant’s CO2 for Enhanced Oil Recovery.
Rentech is developing a [http://www.rentechinc.com/rentech-projects.htm#2 29,600 barrel per day coal and biomass to liquids plant in Natchez Mississippi] which will market the plant’s CO2 for enhanced oil recovery. The first phase of the project is expected in 2011.
DKRW is developing a [http://www.dkrwadvancedfuels.com/fw/main/Medicine_Bow-111.html 15,000-20,000 Barrel Per Day coal to liquids plant in Medicine Bow Wyoming], which will market it plant’s CO2 for enhanced oil recovery. The project is expected to begin operation in 2013.
===Australia===
{{Main|Carbon capture and storage in Australia}}
The federal Resources and Energy Minister Martin Ferguson has opened the first geosequestration project in the southern hemisphere. The demonstration plant is near Nirranda South in South Western Victoria. ({{coord|35.31|S|149.14|E}}) The plant is owned by the CO<sub>2</sub> Cooperative Research Centre. It is funded jointly by government and industry. It aims to store 100,000 tonnes of carbon dioxide extracted from a gas well. Carbon dioxide-rich gas is extracted from a reservoir via a well, compressed and piped 2.25km to a new well. There the gas is injected into a depleted natural gas reservoir approximately two kilometres below the surface. <ref> "First carbon storage plant launched" [http://news.sbs.com.au/worldnewsaustralia//first_carbon_storage_plant_launched_544064]</ref> <ref> "Seeking clean coal science 'only option'" [http://news.theage.com.au/seeking-clean-coal-science-only-option/20080402-237d.html]</ref> This project is tiny by world standards as BP's Algerian plant is storing 1,000,000 tonnes each year.
This plant does not propose to capture CO<sub>2</sub> from coal fired power generation. There is no project anywhere in the world storing CO<sub>2</sub> stripped from the products of combustion of coal burnt for electricity generation at coal fired [[power stations]].
==Limitations of CCS for power stations==
{| class="wikitable sortable"
|+Limitations of Carbon Capture and Storage (CCS) for Power Stations<ref>Rochon, Emily et.al. [http://www.greenpeace.org/raw/content/usa/press-center/reports4/false-hope-why-carbon-capture.pdf False Hope: Why carbon capture and storage won’t save the climate] Greenpeace, May 2008, p.5.</ref>
|-
! Limitation !! Details
|-
| CCS cannot deliver in time to avoid dangerous climate change. || The earliest possibility for deployment of CCS at utility scale is not expected before 2030. To avoid the worst impacts of climate change, global greenhouse gas emissions have to start falling after 2015, just seven years away.
|-
| CCS wastes energy. || The technology uses between 10 and 40% of the energy produced by a power station. Wide scale adoption of CCS is expected to erase the efficiency gains of the last 50 years, and increase resource consumption by one third.
|-
| Storing carbon underground is risky. || Safe and permanent storage of CO2 cannot be guaranteed. Even very low leakage rates could undermine any climate mitigation efforts.
|-
| CCS is expensive. || CCS could lead to a doubling of plant costs, and an electricity price increase of 21-91%. Money spent on CCS will divert investments away from sustainable solutions to climate change.
|-
| CCS carries significant liability risks. || CCS poses a threat to health, ecosystems and the climate. It is unclear how severe these risks will be.
|}
==References==
<div class="references-small">
* [IPCC, 2005] ''IPCC special report on Carbon Dioxide Capture and Storage''. Prepared by working group III of the Intergovernmental Panel on Climate Change. Metz, B., O.Davidson, H. C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. Available in full at [http://www.ipcc.ch/ipccreports/srccs.htm www.ipcc.ch]
*''Environmental Challenges and Greenhouse Gas Control for Fossil Fuel Utilization in the 21st Century''. Edited by M. Mercedes Maroto-Valer ''et al.'', Kluwer Academic/Plenum Publishers, New York, 2002: "Sequestration of Carbon Dioxide by Ocean Fertilization", pg 122. by M. Markels, Jr. and R.T. Barber.
*Nobel Intent: Carbon Dioxide Lakes in the Deep Ocean, September 19, 2006 @ 11:08AM - posted by John Timmer http://arstechnica.com/journals/science.ars/2006/9/19/5341
*Solomon, Semere. (July, 2006). Carbon Dioxide Storage: Geological Security and Environmental Issues Case Study on the Sleipner Gas Field in Norway. The Bellona Foundation. Retrieved November 7th, 2006, from http://bellona.no/filearchive/fil_Paper_Solomon_-_CO2_Storage.pdf
<references/>
* ICO2N - The Vision [[http://www.ico2n.com/docs/tech/ICON%20Vision.pdf]]
</div>
==See also==
{{EnergyPortal}}
{{Portal|Sustainable development|Sustainable development.svg}}
*[[Carbon dioxide sink]]
*[[CO2 sequestration]]
*[[Mitigation of global warming]]
*[[Low-carbon economy]]
*[[Solvay process]] industrial process used in the production of soda ash (sodium carbonate)
*[[FutureGen]]
*[[Lake Nyos]] A possible hazard resulting from a large scale release of CO2
==External links==
*[http://www.ipcc.ch/ipccreports/srccs.htm Intergovernmental Panel on Climate Change] IPCC Special Report on Carbon Dioxide Capture and Storage (CCS).
** [http://www.greenfacts.org/en/co2-capture-storage/index.htm Scientific Facts on CO2 Capture and Storage], a peer-reviewed summary of the IPCC Special Report on CCS.
*[http://www.jsg.utexas.edu/carboncapture/carbonsequestration.html Carbon Sequestration News] Recent news articles on CO<sub>2</sub> capture and storage.
*[http://www.beg.utexas.edu/environqlty/co201.htm Gulf Coast Carbon Center] University of Texas at Austin research center that investigates geologic storage of anthropogenic carbon dioxide in the Gulf Coast region.
*[http://pangea.stanford.edu/~mhesse/NewsLinks.html Stanford University] Collection of recent news articles on CO<sub>2</sub> capture and storage.
*[http://www.bigskyco2.org/ The Big Sky Carbon Sequestration Partnership] The Big Sky Carbon Sequestration Partnership (BSCSP)
*[http://climatechangeaction.blogspot.com/search/label/ccs Webcasts, Reports and Articles] Relevant Climate Change Action Posts
*[http://www.fossil.energy.gov/programs/sequestration/index.html DOE Fossil Energy] Department of Energy programs in carbon dioxide capture and storage.
*[http://www.epa.gov/climatechange/emissions/co2_gs_tech.html U.S. Environmental Protection Agency] Overview of Geologic Sequestration of CO<sub>2</sub>.
*[http://www.epa.gov/climatechange/emissions/co2_geosequest.html U.S. Environmental Protection Agency - Regulating Geologic Sequestration of CO<sub>2</sub> ] U.S. EPA page outlining EPA's role in regulating geologic sequestration of CO<sub>2</sub>.
*[http://assets.opencrs.com/rpts/RL34307_20080415.pdf] US Congressional Research Service report: "Regulation of Carbon Dioxide (CO2) Sequestration Pipelines: Jurisdictional Issues (Updated April 15, 2008) by Adam Vann and Paul W. Parfomak.
*[http://assets.opencrs.com/rpts/RL33971_20080117.pdf] US Congressional Research Service report: "Carbon Dioxide (CO2) Pipelines for Carbon Sequestration: Emerging Policy Issues" by Paul W. Parfomak and Peter Folger.
*[http://www.co2captureandstorage.info/ CO<sub>2</sub> Capture and Storage] International Energy Agency Greenhouse Gas Research Programme (includes CSS project summaries)
*[http://www.co2geonet.com CO2GeoNet] European Network of Excellence on CO<sub>2</sub> Geological Storage
*[http://www.netl.doe.gov/technologies/carbon_seq/core_rd/storage.html CO<sub>2</sub> Capture and Geologic Storage] National Energy and Technology Laboratory summary of worldwide projects
* [http://www.ico2n.com] ICO2N - Canadian Carbon Dioxide Capture and Storage initiative
* {{cite pressrelease | url=http://www.ambafrance-dk.org/article.php3?id_article=966 | title=World’s largest CO2 capture pilot plant inaugurated in Denmark | publisher=[[European Union]] | date=[[2006-03-14]] | accessdate=2007-07-13 }}
[[Category:Carbon dioxide]]
[[Category:Chemical engineering]]
[[Category:Climate change]]
*[http://www.geos.ed.ac.uk/research/sccs/ Scottish Centre for Carbon Storage] Current Carbon Capture and Storage Research being undertaken in Edinburgh, Scotland.
*[http://www.co2storage.org.uk/ UK Carbon Capture and Storage Consortium] Overview of the UK academic consortium focused on researching issues related to Carbon Capture and Storage.
*[http://www.worldcoal.org/pages/content/index.asp?PageID=476 Storing CO<sub>2</sub> Underground]
*[http://www.ceem.unsw.edu.au/content/documents/Diesendorf_Coal-Geoseq.pdf Can geosequestration save the coal industry?]
[[ca:Captura i segrest de dioxid de carbó]]
[[es:Captura y almacenamiento de carbono]]
[[fr:Séquestration géologique du dioxyde de carbone]]
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[[pl:Sekwestracja dwutlenku węgla]]
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[[zh:碳收集及儲存]]